Discovery of a rare flowering plant supports belief that the Grand Canyon is more biologically diverse than previously thought

March 13, 2014

To botanists Wendy Hodgson (Desert Botanical Garden), John Schenk (Tulane University) and Larry Hufford (Washington State University), one does not have to travel to the tropics to find species new to science. Rather, there are many species left to be discovered even in our own backyards.

For several years Hodgson, a Senior Research Botanist and Herbarium Curator at the Garden has been searching for new plant species in the vast maze of channels and ravines that make up the Grand Canyon of Arizona. The team’s discovery of a hitherto unknown flowering plant in one section of the Grand Canyon is described in a recent article in Brittonia, a journal devoted to systematic biology.

The Grand Canyon is biologically diverse, being home to nearly half of the flowering plants found in Arizona - a remarkable statistic considering Arizona is ranked as high as third in the nation with total number of plant species. Several species in the Canyon are rare or are found here and nowhere else in the world. “The Grand Canyon is biologically important with numerous species that have locally evolved within the highly dissected canyon,” says Schenk. “Many of its plant species have narrow distributions and occur only in specific habitats. The obvious challenge to conducting fieldwork in the canyon is the rugged terrain.” Hodgson knows the challenges of Canyon botanizing well, having roamed its rugged terrain during 100+ trips over a span of 20 years searching for and documenting plants. Related studies made by Wendy and colleagues support the notion that many biologists have speculated on, that the Grand Canyon region is not only important geologically, but also biologically.

The newly discovered plant has white to light yellow flowers that bloom from May through November. Its discoverers named it Mentzelia canyonensis after the Grand Canyon, the only place it is known to exist. The plant is a shrubby perennial herb with a taproot adapted to finding moisture in the loose, rocky soils of the canyon’s arid landscape. It is currently only known from the eastern half of the Canyon, seemingly preferring a specific soil type, that being the interface of the Bright Angel Shale and Muav Limestone.

"With more time in the field coupled with more tools such as molecular DNA technologies, we can only expect to increase the number of new species in this botanical hot spot,” says Hodgson. Indeed, the team described another new mentzelia from the Grand Canyon just two years ago, naming it Mentzelia hualapaiensis for the Hualapai Nation. Hodgson also named a new agave, Agave phillipsiana, from the Grand Canyon, believed to be remnants of plants once farmed by pre-Columbian peoples.

“As threats to plant communities increase due to urbanization, habitat alteration, and climate change, describing Earth's biodiversity is increasingly imperative before these species are lost to extinction and gone forever,” says Schenk. “Many of the new species to be discovered are likely to be cryptic, very localized, and rare.”

As well known as the Grand Canyon is, there is still much to learn about its inhabitants, whether it be plants, animals, or past and present cultures. Searching for and documenting new species is a long-term commitment, especially in such vast areas as the Grand Canyon. Working with other scientists such as Schenk and Hufford only increases the quality, depth and breadth of this and other research. In addition, the Desert Botanical Garden continues to collaborate with Grand Canyon National Park and Hualapai Nation in supporting exploration and research in this amazing, visually stunning and biologically diverse place we call Grand Canyon.